Dyeing of polyester fiber



nited States This invention relates to processes for dyeing polyester fiber. By the latter term I am referring to polyester fiber (generally defined as fiber made from a long-chain synthetic polymer composed of at least 85% by weight of an ester of a dihydric alcohol and terephthalic acid, and typified in practice by polyethylene terephthalate) as Well as acid-modified polyester fiber (containing metal sulfonate groups) as described for instance in British Patent No. 826,248 (accepted December 31, 1956).

It is an object of this invention to provide a practical and reasonably rapid method for dyeing polyester fiber with Water-insoluble dyes, such as disperse dyes or other solvent-soluble colors free of ionogenic substituents, at relatively low temperatures. Additional objects and achievements of this invention will appear as the description proceeds.

Hitherto, the normally accepted procedures for dyeing polyester fibers with disperse dyes involved the use of an aqueous dyebath and a dyeing time of at least one hour at boiling temperature. Shorter dyeing times could be achieved by raising the temperature to about 110 to 130 C., using pressure equipment, while the very short dyeing periods required for continuous dyeings were achieved only at temperatures of 130 to 200 C.

Prolonged treatment in the dyebath is obviously unsuitable -for continuous dyeing (for instance, dyeing of piece goods) and is costly from the viewpoint of time and energy consumed, While the higher dyeing temperatures have a degrading effect both on the dye and the fiber.

Attempts to improve the dyeing of the aforementioned fiber with assistants and carriers often give unsatisfactory results, either through altering the properties of the fibers or by degrading the fastness of the dyes. Several processes using non-aqueous solvent media have been proposed for the purpose of decreasing the dyeing time, but the temperatures required in these solvents are high, in the range of 130 to 200 C. At these temperatures many disperse dyes decompose and it has been necessary to add a dye stabilizer to the dyebath. Also, these methods introduce the problem and cost of removing the solvent from the dyed fiber.

Now according to this invention, the aforenoted problems are eliminated and the dyeing of polyester fiber with water-insoluble dyes free of ionogenic substituents is effected neatly and rapidly by employing a dioxane dyebath. In other words, according to my invention the color is dissolved in dioxane, and polyester fiber is dyed in said solution at a temperature between 80 to 105 C. (preferably 95 to 100 C.) for a very short period (usually less than minutes), whereupon the fiber is removed from the dyebath, rinsed with water and dried.

It will be noted that the solvent in my process, di oxane, boils at 101.5 C.; consequently, the temperature of dyeing is automatically limited in its upper range, unless special, reflux or pressure equipment be resorted to. As a result of this lower temperature, the dyes employed do not decompose, and they give even, level dyeings with rapid build-up. Also, the solvent is easily removed from the dyed fabric by rinsing with Water. In addition, the subject process has a distinct advantage in commercial operations inasmuch as steam may be used to heat the dyebath, and it avoids the need of atet costly equipment as required for the presently used high boiling solvents. The subject process is also easily adaptable to continuous dyeing of piece goods.

The dyeing time in my novel process may vary from 1 to 10 minutes depending on the shade desired. Both polyester and acid-modified polyester fibers aredyed in extremely level shades with the good fastness properties inherent in the respective dyes.

Without limiting this invention, the following examples are given to illustrate my preferred mode of operation. Parts mentioned are by weight.

Example 1 A dyebath is prepared by dissolving 1.45 parts of monochloro-4,S-diaminoanthrarufin in 100 parts of 1,4- dioxane which has been previously purified by contacting with potassium hydroxide pellets and filtration. The solution is heated in a glass-lined steel vessel to the boiling point. Polyethylene terephthalate fabric is stirred in the boiling solution for a period of time ranging from 1 to 5 minutes, depending on the depth of shade desired. The fabric is then removed from the dyebath, rinsed with Water, scoured for 5 minutes with an aqueous solution of a surface-active agent (e.g. 1 part of the sodium sulfate of the condensation product of 1 mole of oleyl alcohol with 20 moles of ethylene oxide in 1000 parts of water), and dried.

The resultant blue dyeing is evenly colored in a medium to deep shade, depending upon the dyeing time. It has good fastness properties and a soft hand.

Example 2 A dyebath is prepared as in Example 1, using 0.65 part of 1-amino-4-hydroxy-2-phenoxyanthraquinone dissolved in 100 parts of 1,4-dioxane. Polyethylene terephthala-te fiber dyed in said dyebath for 1 minute at to C. possesses a level, medium-red shade, showing good fastness properties.

Example 3 A dyebath is prepared as in Example 1, using, per 100 parts of dioxane, 1.95 parts of the disazo dye prepared by coupling diazotized aniline to 2,5-dimethoxyaniline, diazotizing the amino azo dye formed and further coupling to phenol. Polyethylene terephthalate dyed in the nearly boiling dyebath for 1 minute possesses a level, deep orange shade, showing good fastness properties.

Example 4 A dyebath is prepared as in Example 1 using the disazo color named in Example 3. Acid-modified polyethylene terephthalate fabric dyed in said bath for 1 to 10 minutes at a temperature near the boiling point (say, at 95 to 101 0.), possesses a level, orange dyeing of medium to deep orange shade (depending on the length of dyeing) which is slightly brighter than the dyeings obtained on unmodified polyester fiber.

In similar manner other disperse dyes may be applied to polyester fiber according to the procedures of the above examples. Disperse dyes may be defined as water-insoluble organic colors which are normally applied to the fiber from near-colloidal aqueous dispersion. Such dyes have in earlier days been referred to generally as acetate dyes; see the Chemistry of Synthetic Dyes and Pigments, edited by H. A. Lubs, pp. 167-474.

As further illustrations of practical dyes coming within the purview of this invention may be named:

Monochloro-4,S-diaminochrysazin, (Blue) 1,4-diamino-N- 3-methoxypropyl -2,3-anthraquinonedicarboximide (U.S.P. 2,753,356) (Blue) 1,4-dia-mino-N- 3 -hydroxypropy1) -2,-3 -anthro quinonedicarboximide (U.S.P. 2,628,963) (Blue) 1,4-diamino-N- 2-hydroxyethyl) -2, 3 -anthraqui11onedicarboximide U.S.P. 2,628,963) (Blue) 1,4-dianilinoanthraquinone (Violet) 1-anilino-4-hydroxyanthraquinone (Violet) 1,4-diamino-2,3-diphenoxyanthraquinone (Bordeaux) 3-hydroxyquinophthalone (Yellow) In the dyeing procedure, temperatures somewhat below the boiling point of the dyebath have been specified in the above examples, purely for the purpose of minimizing evaporation of the solvent. Where, however, the available equipment Will permit it, slightly higher temperatures, say up to 105 C. or even 110 C., can be used without danger of injuring the fiber or decomposing the color. If an open vessel is employed, a dyeing temperature of 95 to 100 C. is recommended.

I claim as my invention:

1. A process of dyeing textile fiber of the group consisting of polyethylene terephthalate fiber and su-lfonate modified polyethylene terephthalate fiber, which comprises applying thereto a dyebath consisting of a solution of a disperse dye in dioxane, said application of the dyebath being effected at about the boiling point of the dyebath.

2. A process of dyeing textile fiber of the group consisting of polyethylene terephthalate fiber and sulfonate modified polyethylene terephthalate fiber, which comprises applying thereto at a temperature of to (3., a dioxane solution of a disperse dye, said dioxane constituting the sole solvent in said solution, and following said application by rinsing the dyed fiber with water and drying.

References Cited in the file of this patent UNITED STATES PATENTS 2,524,811 Koberlein Oct. 10, 1950 2,909,177 Dowd et a1. Oct. 20, 1959 2,916,345 Hees Dec. 8, 1959 

1. A PROCESS OF DYEING TEXTILE FIBER OF THE GROUP CONSISTING OF POLYETHYLENE TEREPHTHALATE FIBER AND SULFONATE MODIFIED POLYETHYLENE TEREPHTHALATE FIBER, WHICH COMPRISES APPLYING THERETO A DYEBATH CONSISTING OF A SOLUTION OF A DISPERSE DYE IN DIOXANE, SAID APPLICATION OF THE DYEBATH BEING EFFECTED AT ABOUT THE BOILING POINTOF THE DYEBATH. 